Micro-electro-mechanical switch beam construction with minimized beam distortion and method for constructing

ABSTRACT

Disclosed is a micro-electro-mechanical switch, including a substrate having a gate connection, a source connection, a drain connection and a switch structure, coupled to the substrate. The switch structure includes a beam member, an anchor, an anchor beam interface and a hinge. The beam member having a length sufficient to overhang both the gate connection and the drain connection. The anchor coupling the switch structure to the substrate. The anchor beam interface coupling the anchor to the hinge. The hinge coupling the beam member to the anchor at a respective position along the anchor&#39;s length, the hinge to flex in response to a voltage differential established between the gate and the beam member. The switch structure having gaps between the substrate and the anchor in regions proximate to the hinges.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/755,285, filed on Apr. 6, 2010, which is a continuation-in-part ofU.S. patent application Ser. No. 12/338,767, filed on Dec. 18, 2008, nowU.S. Pat. No. 8,294,539. The disclosure of these previous applicationsis incorporated herein by reference in its entirety.

BACKGROUND

The present invention is directed to a micro-electro-mechanicalswitching (MEMS) device having a beam that is actuated in a mannersimilar to an electrical relay, and specifically, to such a MEMS devicebeam having structures, and constructed in a manner, to minimize thedistortion of the beam when subject to thermal expansion.

Due to the small size of a MEMS device and the materials from which itis made, the parts of the device are subject to closer tolerances andexperience the effects of the environment much more greatly than largerdevices. The MEMS device is made, preferably, from gold because of itselectrical conducting properties and silicon for suitability forintegrated circuit fabrication. The gold and silicon have differentproperties and are affected by the environment in different ways. Inparticular, when a MEMS device is manufactured and operated, it issubject to a variety of environmental conditions, such as excessiveheat. When subject to excessive heat, the gold and silicon from which aMEMS device are made expand at different rates, which can causedistortion in the structure of the MEMS device. This material expansionand resulting distortion can be compensated for during the designprocess but only to a certain degree.

For example, the linear expansion of a material AL due to temperaturecan be determined fromΔL=α.L0.ΔTwhere α is the coefficient of thermal expansion, L0 is the length at theinitial temperature, and ΔT is the change in temperature.

A configuration of a conventional MEMS switch is shown in FIG. 1 in across-sectional view. The MEMS switch 100 comprises a substrate 110 anda switch 120. The substrate 110 is formed from a semiconductor materialsuch as silicon and coated with a dielectric material such as silicondioxide or the like. The substrate 110 can also be a dielectric materialsuch as sapphire or the like. The switch 120 includes an anchor 121, ahinge 123, a beam 125, and a tip 127. The anchor 121 couples the switch120 to the substrate 110. The switch 120 also forms a current path ortrace comprising the anchor 121, the hinge 123, the beam member 125, andthe tip 127. The switch 120 is formed from gold, or some other suitableconductor. The current path via the anchor 121 is electrically connectedto a source connection 113. The switch 120 is actuated by a voltageapplied to a gate connection 115. The hinge 123 flexes in response tothe voltage differential established between the gate connection 115 andthe beam member 125 by the applied voltage. In response to the flexing,the tip 127 contacts the drain connection 117, completing a current pathfrom a source connection 113 to the drain 117. Of course, the sourceconnection 113 and the drain connection 117 can be interchanged withoutsubstantially affecting the operation of the MEMS switch 110. As theelectric field at the gate connection 115 dissipates, the beam 125raises thereby lifting the tip 127 from the drain connection 117.

During manufacturing, the MEMS device 100 can be subjected to high heat,such as approximately 400° C., which may cause distortion of thecomponents of the MEMS device 100. Also, in operation, the MEMS device100 will begin to experience heat, or thermal effects, associated withthe application of voltage at gate connection 115 and electrical currentthrough the current path from source connection 113 to drain connection117, as well as heat from other sources on the substrate 110 or nearby,or even from the environment. In some cases of distortion, the beam 125will lower toward the gate 115 due to thermal expansion and the tip 127will contact drain connection 117. Although described with respect to asingle switch, it is understood that the MEMS device 100 can comprisemore than one switch 120 on a substrate 100, and the above descriptionshould not be interpreted to be limited to a single switch. In cases ofmultiple MEMS devices configured adjacent to one another, the beam 125will distort such that the deflection of the tip 127 is different fromthat of neighboring tips. Such non-uniform deflection can be due tonon-symmetric mechanical constraints, non-uniform fabrication processvariations, other non-optimal operating conditions, other reasons,and/or combinations thereof. The non-uniform deflection may result, forexample, in all tips 127 not making uniform contact, which can causevariations in the voltage required to actuate a particular switch incomparison to the voltage required to actuate other switches.

At the gold-substrate interface at an anchor point in a MEMS device,there is a difference in thermal expansions. Gold expands at almost 5times the rate of silicon, and nearly 10 times the rate of silicondioxide (SiO2). So there is a thermal expansion differential atdiffering points, such as the anchor point, of the MEMS device, withgold expanding the most. For example, at the gold-substrate interface,gold expands by approximately 0.56% when a temperature of 400° C.differential is applied, while silicon expands by approximately 0.12%.The difference in thermal expansion causes a shear force between themwhich can contribute further to distortion in the MEMS device andpossibly device failure.

Because the substrate will not bend in the normal bimetallic fashion dueto its much larger mass (i.e., the whole wafer), it is expected the goldat the interface would expand approximately 0.12%, although understress, whereas the gold at the top of the MEMS device would expand atapproximately 0.56%. This thermal expansion mismatch between the top andthe bottom of anchor 121 is problematic because the distortion of anchor121 may cause displacements in the beam 120 and the tip 127. If thethermal displacement at the tip 127 equals the separation distancebetween the tip 127 and the drain 117, the source 113 and the drain 117will become electrically short-circuited. Further distortion at theanchor 121 will induce mechanical stresses in the beam 120 and the tip127. Again, distortion caused by thermal expansion can cause performanceproblems in the MEMS device 100.

Another problem resulting from unmitigated thermal expansion is atendency, in cases of multiple MEMS devices is for the beams 120 of MEMSdevices to spread apart, in a shape similar to a hand-held fan, from oneanother in the horizontal plane. The spreading apart can causemisalignment of the components of the MEMS devices. Because ofnon-symmetric mechanical boundary conditions among the beams 120, suchspreading apart will cause non-uniform tip displacements.

Accordingly, there is a need in the art to address the thermal expansionand distortion of the structures in the MEMS device, and thereby reducecomplexity of associated circuitry that attempts to overcome the effectsof the distortion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross sectional view of a conventional MEMS device.

FIGS. 2A and 2B illustrate, respectively, a cross sectional view and arear view of a MEMS device according to an exemplary embodiment of thepresent invention.

FIG. 3 illustrates a rear view of a MEMS device according to anotherexemplary embodiment of the present invention.

FIG. 4 illustrates a top view of a configuration of the beams of a MEMSdevice according to another exemplary embodiment of the presentinvention.

FIGS. 5A and 5B illustrate a buttress configuration of the anchor from across sectional view and from a top view of a MEMS device according toan exemplary embodiment of the present invention.

FIG. 6 is a top-view of an exemplary configuration of the anchor of aMEMS device according to an embodiment of the present invention.

FIG. 7 illustrates a top-view of an exemplary configuration of a beam ofa MEMS device according to an embodiment of the present invention.

FIG. 8 illustrates a three-dimensional plane view of an exemplaryconfiguration of the beam and anchor of a MEMS device according toanother embodiment of the present invention.

FIG. 9 illustrates a plan view of an exemplary configuration of ananchor airbridge tie shown according to an embodiment of the presentinvention.

FIG. 10 illustrates a sectional view of an exemplary configuration ofthe anchor airbridge tie shown in FIG. 9 according to an embodiment ofthe present invention.

FIG. 11 illustrates a top-view of an exemplary configuration of a beamof a MEMS device according to yet another embodiment of the presentinvention.

FIG. 12 illustrates a method for producing a switch according to anexemplary embodiment of the present invention.

FIG. 13 illustrates a three-dimensional plane view of an exemplaryconfiguration of the beam and anchor of a MEMS device according to yetanother embodiment of the present invention.

FIG. 14 illustrates a three-dimensional plane view of an exemplaryconfiguration of the beam and anchor of a MEMS device according to afurther embodiment of the present invention.

FIG. 15 illustrates a sectional view of an exemplary configuration ofthe beam and anchor of a MEMS device shown in FIG. 14 according to afurther embodiment of the present invention.

FIG. 16 illustrates a top-view of an exemplary configuration of the MEMSdevice according to a further embodiment of the present invention.

FIG. 17 illustrates a sectional view of an exemplary configuration ofthe beam and anchor of a MEMS device according to another embodiment ofthe present invention.

FIG. 18 illustrates a cross-sectional view of an exemplary configurationof the beam and anchor of a MEMS device according to another embodimentof the present invention.

DETAILED DESCRIPTION

To overcome the problems associated with distortion caused by thermalexpansion of components of the MEMS device, the disclosed constructioncan mitigate the effects of thermal expansion of the device, and providea MEMS device having minimized distortion while maintaining itsoperating characteristics. This is accomplished by providing voids in ananchor behind a hinge of a MEMS device and reducing the quantity of massof the anchor, both of which minimize the effects of thermal expansion.

Embodiments of the present invention relate to amicro-electro-mechanical switch, and may include a switch structurecoupled to a substrate. The substrate may have a gate connection, asource connection and a drain connection. The switch structure mayinclude a beam member, an anchor, an anchor beam interface and a hinge.The beam member may have a length sufficient to overhang both the gateconnection and the drain connection of the substrate. The anchor mayhave a first thickness, and may couple the switch structure to thesubstrate. The anchor may have an anchor slot that extends through theanchor to the substrate. The anchor beam interface may have a secondthickness, and may be coupled to the anchor. The second thickness may begreater than the first thickness. The hinge may couple the beam memberto the anchor beam interface, and may be configured to flex in responseto a voltage differential established between the gate connection andthe beam member. The hinge may be offset from the anchor beam interfacein a vertical plane at an anchor beam interface end located between theanchor beam interface and the hinge.

Another embodiment of a micro-electro-mechanical switch may include aplurality of switch structures coupled to a substrate, which may have aplurality of gate connections and a plurality of drain connections. Theplurality of switch structures may include a plurality of beam members,an anchor, a plurality of anchor slots, a plurality of anchor beaminterfaces, and a plurality of hinges. The plurality of beam members mayeach have a length sufficient to overhang a respective gate connectionand a respective drain connection of the plurality of gate connectionsand plurality of drain connections of the substrate. Each individualbeam of the plurality of beams may be connected to an adjacent beam by across connection member that forms an open slotted region that separatesthe adjacent beams from one another. The anchor, which may have a firstthickness, may be coupled to the substrate. The plurality of anchor beaminterfaces may couple the anchor to the plurality of beams. The anchorbeam interfaces may have a second thickness different from the firstthickness of the anchor. The plurality of anchor slots may be located inthe anchor proximate to a respective one of the plurality of anchor beaminterfaces. The plurality of hinges may each be offset in the verticalplane from the anchor beam interface, and may be coupled to a respectiveone of the plurality of anchor beam interfaces and to a respective oneof the plurality of beam members. Each of the hinges may be configuredto flex in response to a voltage differential established between arespective one of the gate connections and the beam member. Theplurality of hinges may have a thickness that is the same as the secondthickness.

FIGS. 2A and 2B illustrate a configuration of a MEMS device according toan exemplary embodiment of the present invention. FIG. 2A illustrates across-sectional view of the MEMS device. The cross section of FIG. 2A istaken at sectional 2A shown in FIG. 2B. The MEMS device 200 comprises asubstrate 210 and a switch 220. The switch 220 includes an anchor 221, ahinge 223, a beam 225, and a tip 227. The anchor 221 couples the switch220 to the substrate 210. The switch 220 also forms a current path ortrace comprising the anchor 221, the hinge 223, the beam member 225, andthe tip 227. The switch 220 is formed from gold, or some other suitableconductor. The current path via the anchor 221 is electrically connectedto a source connection 213.

The switch 220 is actuated by a voltage applied to a gate connection215. The hinge 223 flexes in response to the voltage, or charge,differential established between the gate connection 215 and the beammember 225 by the applied voltage. In response to the flexing, the tip227 contacts the drain connection 217, completing a current path from asource connection 213 to the drain 217. Of course, the source connection213 and the drain connection 217 can be interchanged withoutsubstantially affecting the operation of the MEMS switch 210. As theelectric field at the gate connection 215 is taken away, the beam 225raises thereby lifting the tip 227 from the drain connection 217. Theanchor 221 of the switch is configured to include a gap 222 that extendslaterally through the anchor 221. The gap 222 can have the samedimensions from the rear of the anchor 221 to the front of the anchor221. Of course, the dimensions of the gap 222 in anchor 221 may varyfrom wider to narrower and vice versa in all directions, i.e., front torear, rear to front, up to down or down to up. Specifically, the gap 222may have various heights in the Z-axis that extend from a pointsubstantially co-planar with source connection 213 to a point co-planarwith the bottom of hinge 223 and/or beam 225. In addition, the shapedoes not have to be rectangular, but may be circular, polygonal,cylindrical, triangular or any shape that provides suitablestress-relieving properties.

The gap 222 may be located beneath the hinge 223, but does notnecessarily have to be located precisely beneath the hinge 223. Thealignment of the gap 222 and the hinge 223 can be readily seen in FIG.2B. FIG. 2B is a rear view of a MEMS device 200 according to anexemplary embodiment of the present invention. As illustrated in FIG.2B, the gap 222 may be aligned to be substantially centered, although itis not required to be, in a vertical plane beneath the hinge 223. Othergap 222 configurations are possible, such as conical or cylindrical.

FIG. 3 illustrates another rear view of a MEMS device according toanother exemplary embodiment of the present invention. In thisembodiment, gaps 322 may be provided between the substrate 310 and theswitch 320 in an area behind a beam 325. The gaps 322 need not beentirely void of interconnecting structures between the substrate 310and a top surface of the gap 322A. Accordingly, the gap may include oneor more center pillars 332, which assist to keep the top surface of thegap spaced from the substrate. The center pillars 332 are shown to berectangular in shape, but can be a linear rib extending in the Y-axis.Alternatively, a rib may extend across a width of the gap 322 in theX-axis.

FIG. 4 illustrates a configuration of beams of a MEMS device from a topview of the MEMS device according to another exemplary embodiment of thepresent invention. The exemplary MEMS device 400 comprises an anchor410, a plurality of hinges 412, a plurality of beams 415, a plurality ofslots 417 and beam connection cross members 419. The slots 417 can belocated between adjacent beams 415. When experiencing the stress ofthermal loads, the illustrated configuration allows for expansion of aportion of the beams 415 into the slots 417. The beam connection crossmembers 419 connect adjacent beams 415 to one another and providesupport of the beams 415 to provide structural support by minimizing,for example, any possible rotation, tilting or twisting of the beams415. The beam cross connection members 419, although shown centered onbeams 415, may be located at any point along the beams 415 in theY-axis.

FIGS. 5A and 5B illustrate a buttress configuration of an anchor from across sectional view and from a top view of a MEMS device, respectively,according to an exemplary embodiment of the present invention. The crosssection of FIG. 5A is taken at sectional 5A shown in FIG. 5B. The MEMSdevice 500 comprises a substrate 510 and a switch 520. The switch 520comprises an anchor 521, a gap 522, a hinge 523, a beam 525 and a tip527 similar to those discussed above with respect to FIGS. 1-4. Theanchor 521 further comprises a buttress 532. As illustrated in FIG. 5A,the buttress 532 extends from the top e of the anchor 521 to thesubstrate 510, and is on the side of the anchor 521 closer to the hinge523 and beam 525.

In the absence of the buttress 532, the material forming the top (i.e.,the highest point in the Z-axis) of the anchor 521 can expand, whensubject to the thermal stresses, in the direction of the beam 525resulting in a rolling action of the anchor 521. The rolling action maybe toward the beam 525. The buttress 532 serves to allow for expansionof the anchor 521, but also serves to block the rolling forward of theanchor 521 and the resulting sagging of the beam 525. The additionalmass provided by the buttress 532 of the anchor 521 assists in limitingthe amount of expansion.

Although shown in FIG. 5B as two buttresses aligned side-by-side in ahorizontal direction, the buttress 532 can, alternatively, be alignedone-above-the-other in a vertical direction. Of course, the buttress 532be a single buttress or more of the same or different sizes and shapes.Furthermore, as illustrated the buttress 532 is shown having arectangular shape, however, the buttress can have 532 any shape such ascurved, saw-toothed, sinusoidal, polygonal and the like, suitable forproviding additional structural support for mitigating distortion withinthe MEMS device 500.

Also shown in FIG. 5B are beam connection cross members 539 that connectbeams 525. Although shown substantially at the midpoint of the beams525, the beam connection cross members 539 may be located at any pointalong the beam 525 between the tip 527 and hinge 523. The beamconnection cross members 539 may act to provide a restoring force to thebeams 525, thereby aiding in maintaining proper positioning of the beams525. Locating the beam connection cross members 539 closer to the tipprovides additional stress relief, and allows the material from whichthe beams 525 is formed to expand into beam slots 537.

FIG. 6 illustrates a top-view of a configuration of a beam of a MEMSdevice according to another exemplary embodiment of the presentinvention. In the embodiment illustrated in FIG. 6, the MEMS device 600comprises a substrate 605, an anchor 621, a hinge 623, a beam 625, a tip627 and an optional beam connection cross member 624. The beam 625 has alength that is reduced in comparison to the beams illustrated in theembodiments of FIGS. 1-5. It is preferable that the beam 625 have alength of approximately 50 micrometers, which is less than the length ofthe beam s in the embodiments of FIGS. 1-5. The beams 625 in theembodiments of FIGS. 1-5 are approximately 100 micrometers. The reducedlength and reduced mass of the beam 625 of the present embodimentfacilitates a structurally more rigid beam with less beam cantileveredfrom the hinge 623. The reduced cantilever reduces stress on the hinge623 thereby limiting the effects of any thermal expansion.

In addition, the width W₁ of beam 625 may also vary and the width W₂ mayalso vary. The width W₁ may be either greater or equal to the width W₂.Furthermore, the optional beam connection cross members 624, if present,do not have to be centered on the beams 625, but may be located at anypoint along the beam 625 either closer to tip 627 or closer to hinge623. In addition, the locations or absence of optional beam connectioncross members 624 may alternate from one beam to the next beam acrossMEMS device 600.

FIG. 7 is a top-view of a configuration of the anchor of a MEMS deviceaccording to an exemplary embodiment of the present invention. The MEMSdevice 700 comprises a substrate 705 and an anchor 710. The anchor 710includes anchor slots 715 and beam 720. The beam 720 interfaces with theanchor 710 via the hinge 719. The anchor slots 715 reduce the amount ofmass of the anchor 710, thereby limiting the amount of material that canexpand. In addition, the anchor 710 can expand into the anchor slots715. This reduces the distortion of the anchor 710 and the hinge 719and, as a result, reduces the tilting, either down or up, of the beams720.

The anchor slots 715 are preferably substantially aligned with hinges719, and extend to the substrate 705. Of course, the dimensions of theanchor slot 715 may vary from wider to narrower and vice versa in alldirections, i.e., top-to-bottom or bottom-to-top. In addition, the shapeof the anchor slot 715 does not have to be rectangular, but can becircular, polygonal, cylindrical, triangular or any shape that providessuitable stress-relieving properties, nor do the anchor slots 715 haveto be of uniform size. It is also envisioned that the anchor slots 715can be various shapes and sizes, or uniform shapes and sizes, or acombination of both in the exemplary embodiments. Furthermore, theanchor slot 715 does not have to be a single slot aligned with the hinge720, but can be a plurality of anchor slots 715 substantially alignedwith the hinge 720 or in a number of different locations in the anchor710, or a combination of both. The anchor slot 715 does not have to belocated directly behind hinge 719. By minimizing the mass of the anchor710, the gold or other material, from which the anchor 710 is made, doesnot expand as much. Furthermore, the anchor slots 715 provide additionalspace into which the gold or other material can expand.

In another embodiment, the anchor 821 includes a U-shaped anchor slot815. In FIG. 8, the MEMS device 800 comprises a switch 820 and an anchor821. The switch 820 comprises an anchor beam interface 825, a hinge 823,a beam 826, a beam cross connection member 824; a tip 827 and an anchorairbridge tie 830. The anchor beam interface 825 is the attachment pointfor the hinge 823 to the anchor 821. The hinge 823 extends, in the Yaxis, between the anchor beam interface 825 to connect with beam 826including expansion hole 828. The beam 826 is connected to an adjacentbeam 826A by a beam cross connection member 824. As illustrated, switch820A can be connected to yet another switch 820B by another beam crossconnection member 824A, which in turn is connected to a further switch820C.

Due to the high heat that the switch 820 experiences duringmanufacturing and operation, the anchor 821 and other portions of switch820 may expand and may reduce the size of the U-shaped anchor slot 815,this aids in preventing warping and other detrimental effects to thebeam 826. Thereby allowing the MEMS device 800 to operate properly.Cross connection member 824 connects switch 820 to switch 820A at beam826 and beam 826A. Switch 820A comprises, similar to switch 820, acommon anchor 821, an anchor slot 815A, a beam 826, a hinge 823, a beaminterface 825A, and a tip 827. Switches 820B and 820C are similarlyconstructed. The beam cross connection member 824 improves thestructural stability of the beams by aiding in mitigating the effects ofthe thermal expansion to which the MEMS devices are subjected. Beamcross connection members 824 and 824A may have different positions frombeam-to-beam along the beams 826 and 826A. The position of beam crossconnection members 824 and 824A influence the dimensions of beam slot829 located between the beams 826 and 826A and beam slot 829A betweenbeams 826A and 826B. The length of the beam slots 829 and 829A may bemeasured from the beam cross connection member 824 to the end of thebeam 826 at the point where hinge 823 interfaces with the beam 826 inthe Y-axis. Positioning the beam cross connection member 824 closer tothe end of the beam 826 near tip 827 mitigates the thermal effects andstresses on hinge 823 better than positioning the beam cross connectionmember 824 closer to the hinge 823. As shown in FIG. 8, the beam crossconnection members 824 and 824A may alternately be positioned furtheraway from hinge 823 when connecting beam 826 to beam 826A, and closer tohinge 823A when connecting beam 826A to beam 826B. Additionally, beamcross connection members 824 and 824A aid in providing a restoring forceto the beams 826 and 826A to maintain proper alignment and tip 827displacement. The dimensions of beam cross connection members 824 and824A in the X-axis may also be approximately 2-25 micrometers. Thesectional view A illustrates the structure of the beam interface 825Aand the anchor 821. Illustrated with the switch removed, theconfiguration of the anchor 821 comprises U-shaped anchor slots 815 andan anchor airbridge tie 830 is shown.

FIG. 9 illustrates a plan view of an exemplary configuration of aslotted anchor and an anchor airbridge tie according to an embodiment ofthe present invention. The MEMS device 900 comprises a switch 920 and ananchor 921. The anchor 921 includes at least one anchor slot 915, and atleast one anchor section 921A, at least one anchor section 921B, and atleast one anchor airbridge tie 930. For purposes of the followingdiscussion, beam 920 is shown in dashed lines since the focus of thediscussion is the anchor 921, anchor slot 915 and the anchor airbridgetie 930. The anchor airbridge tie 930 spans anchor slot 915 tyingtogether anchor sections 921A and 921B. An air gap can also be locatedbeneath the anchor airbridge tie 930 to further increase space forthermal expansion of materials into anchor slot 915.

This structure can be formed of dual layers of gold. The beam 920 can beformed of gold and have a thickness of approximately 6 micrometers,while the anchor 921 can also be formed of gold and have a thickness ofapproximately 2 micrometers. This dual-thickness, dual layerconfiguration results in differing amounts of thermal expansion for thebeam 920 as compared to the anchor 921. These dimensions are exemplaryfor purposes of discussion, and the exemplary embodiments are notlimited to these dimensions. Of course, other materials or combinationsof materials may be used to form the anchor, anchor airbridge tie, hingeand beam.

The anchor airbridge tie 930 may provide structural rigidity to theanchor 921 thereby allowing for thermal expansion of the gold materialand mitigates warping of the beam 920. An additional feature of theembodiment shown in FIG. 9 is a beam 920 that has the same dimensions asthe anchor 921, and can function without a hinge element.

FIG. 10 illustrates a detailed sectional view of the exemplary anchorairbridge tie 930 shown in FIG. 9 according to an embodiment of thepresent invention.

Sectional view A of the MEMS device 1000 shows in detail an exemplaryanchor 1021 and exemplary beam interface 1025. The anchor 1021 may beformed in various shapes, such as a U-shape or rectangular blocks, andcomprises an anchor slot 1015, an anchor 1021, and anchor airbridge tie1030. The anchor 1021 may include anchor sections 1021A, 1021B and,depending upon its configuration, optional anchor section 1021C. Whenthe anchor slot 1015 is U-shaped, the anchor section 1021C may beintegral with anchor sections 1021A and 1021B to form a monolithicanchor 1021. Alternatively, the individual anchor sections 1021A, 1021Band 1021C may be formed separately and configured as shown. The beaminterface 1025 spans over the anchor airbridge tie 1030 and is supportedby anchor sections 1021A and 1021B.

Anchor slot 1015 may be formed with an open end on both sides of theanchor sections 1021A and 1021B, and separates anchor section 1021A fromanchor section 1021B. When the anchor 1021 is formed with only anchorsections 1021A and 1021B, the anchor airbridge tie 1030 connects theanchor section 1021A with anchor section 1021B by spanning anchor slot1015. This forms a shape similar to the letter H. Optionally, the anchorslot 1015 may be formed to have a U-shape when anchor section 1021Cfills the gap between anchor section 1021A and anchor section 1021B.

The dimensions of anchor airbridge tie 1030 may vary. As shown in FIG.10, the anchor airbridge tie 1030 includes tie extension 1030A and tiewall 1030B. The width W of the anchor airbridge tie expansion 1030A canbe varied to account for differences in the dimensions of a beam, ahinge, a hinge interface 1025, a beam cross connection member, an anchoror any combination thereof as well as to account for the thermalexpansion of different materials used to construct a MEMS device 1000.The adjustment in width W is preferably in the Y-axis. However,adjustments in the X- or Z-axis can also provide substantial results. Inaddition, the length L of the tie wall 1030B may also be varied toprovide additional stress relief properties to the beam and the hingeinterface 1025. Further adjustments of the position of anchor bridge tie1030 in the Y-axis with similar adjustments to the hinge interface 1025along the anchor sections 1021A and 1021B may be made for a variety ofreasons, such as providing additional stress relief or thermalproperties. In one embodiment, the anchor airbridge tie extension 1030Amay be located at an upper most location on the Y-axis, in closeproximity to the beam, such that the tie extension 1030A and the tiewalls 1030B form an inverted U-shape. The width of both the tieextension 1030A or the tie walls 1030B may vary.

FIG. 11 illustrates a top-view of an exemplary configuration of a beamof a MEMS device according to yet another embodiment of the presentinvention.

The configuration of MEMS device 1100 comprises anchors 1121 and beams1120. The beams 1120 together form a flat spring having a thickness (inthe Z-axis) of approximately 2-10 micrometers. The beam 1120 comprises atip 1127, a hinge 1123, a beam cross connection member 1124 and a beaminterface 1125. Similar to a spring, the beam 1120 expands and contractsaccording to the thermal expansion (and contraction) of the MEMS device1100. Due to the beam thermal expansion slots 1117 can fill with gold asthe gold forming the beams 1120 expand. The beam connection crossmembers 1124 can also expand into the beam thermal expansion slots 1117.In addition, the beam connection cross members 1124 provide additionalstructural support to maintain the alignment of tip 1127 with thecontacts at the base (not shown). The flat spring shape of the beams1120 is maintained by the beam cross connection members 1124, and theflat spring shape distributes stress throughout the beams 1120. Stressbeing equal to force over area. The beams 1120 expand into the beamthermal expansion slots 1117 which further reduces stress because thethermal expansion slots 1117 enable the material to move according tothe force induced by the stress caused by thermal expansion. The beamcross connection members 1124 may also act to keep the individual beams1120 from splitting apart. To maximize the stress reduction propertiesof this configuration, the beams 1120 of MEMS device 1100 aresymmetrical around line 1190, which bisects the MEMS device 1100. Ofcourse, asymmetrical beam configurations are also envisioned, and mayprovide stress reduction properties as well. Although MEMS device 1100is shown with three hinges 1123, more or less hinges 1123 may be used.

FIG. 12 illustrates a method for producing a switch according to anexemplary embodiment of the present invention. The exemplary method ofmanufacturing or constructing a micro-electro-mechanical device will bedescribed with reference to FIG. 12. In step 1210, a substrate is formedhaving a plurality of electrical connections including a sourceconnection, a gate connection and a drain connection. An anchor isaffixed, at step 1220, to the substrate at a first point and a secondpoint. The anchor can be electrically connected, at step 1230, to thesource connection. In step 1240, a gap is formed at a location betweenthe first point and the second point. A movable hinge is connected, atstep 1250, to the anchor at a point diagonally opposite the gap in theanchor. At step 1260, a beam is connected to the hinge, the beam havinga width that is wider than the hinge, and configured to move when avoltage is applied to the gate connection. Step 1270 includes connectinga contact tip to the beam, opposite the hinge, that electricallycontacts the drain connection thereby forming a current path formed fromthe source connection to the drain connection, when the beam moves inresponse to a voltage applied to the gate connection.

In yet another embodiment, the anchor beam interface 1325 may beconfigured differently. In FIG. 13, the MEMS device 1300 comprises aswitch 1320 and an anchor 1321. The switch 1320 comprises an anchor beaminterface 1325, a hinge 1323, a beam 1326, a beam cross connectionmember 1324, and a tip 1327. The anchor beam interface 1325 may be theattachment point for the hinge 1323 to the anchor 1321. The hinge 1323may extend, in the Y axis, between the anchor beam interface 1325 toconnect with beam 1326. The beam 1326 is connected to an adjacent beam1326A by a beam cross connection member 1324. As illustrated, switch1320A may be connected to yet another switch 1320B by another beam crossconnection member 1324A, which in turn is connected to a further switch1320C.

Due to the high heat that the switch 1320 experiences duringmanufacturing and operation, the anchor 1321 and other portions ofswitch 1320 may expand and may reduce the size of the U-shaped anchorslot 1315, this aids in preventing warping and other detrimental effectsto the beam 1326. Thereby allowing the MEMS device 1300 to operateproperly. Cross connection member 1324 connects switch 1320 to switch1320A at beam 1326 and beam 1326A. Switch 1320A comprises, similar toswitch 1320, a common anchor 1321, an anchor slot 1315A, a beam 1326A, ahinge 1323A, an anchor beam interface 1325A, and a tip 1327. Switches1320B and 1320C are similarly constructed. The beam cross connectionmember 1324 improves the structural stability of the beams by aiding inmitigating the effects of the thermal expansion to which the MEMSdevices are subjected. Beam cross connection members 1324 and 1324A mayhave different positions from beam-to-beam along the beams 1326 and1326A. The position of beam cross connection members 1324 and 1324Ainfluence the dimensions of beam slot 1329 located between the beams1326 and 1326A and beam slot 1329A between beams 1326A and 1326B. Thelength of the beam slots 1329 and 1329A may be measured from the beamcross connection member 1324 to the end of the beam 1326 at the pointwhere hinge 1323 interfaces with the beam 1326 in the Y-axis.Positioning the beam cross connection member 1324 closer to the end ofthe beam 1326 near tip 1327 mitigates the thermal effects and stresseson hinge 1323 better than positioning the beam cross connection member1324 closer to the hinge 1323. The beam cross connection members 1324and 1324A may alternately be positioned further away from hinge 1323when connecting beam 1326 to beam 1326A, and closer to hinge 1323A whenconnecting beam 1326A to beam 1326B. Alternatively, the beam crossconnection members 1324 and 1324A may extend the entire length of thebeam 1326 and 1326A, respectively. Additionally, beam cross connectionmembers 1324 and 1324A aid in providing a restoring force to the beams1326 and 1326A to maintain proper alignment and tip 1327 displacement.The dimensions of beam cross connection members 1324 and 1324A in theX-axis may also be approximately 2-25 micrometers. The sectional view Aillustrates the structure of the anchor beam interface 1315A and theanchor 1321. Illustrated with the switch removed, the configuration ofthe anchor 1321 comprises U-shaped anchor slots 1315A is revealed. Inthe illustrated embodiment, the anchor beam interface 1325 has a similarthickness to the hinge 1323.

In a further embodiment, the anchor beam interface 1325 may be built upto allow for expansion in a manner that prevents distortion of the beamand the resultant change in distance between the contact tip and thecontact on the substrate. As illustrated in FIG. 14, the MEMS devicestructure 1400 comprises a switch 1420, a substrate 1450 and conductorpaths 1441, 1443 and 1445. The switch 1420 comprises an anchor 1421, ahinge 1423, an anchor beam interface 1425, an anchor beam interface end1425A, a beam 1426, and a contact tip 1427. The anchor 1421 may be aseparate layer of conductive material, such as gold, that is in contactwith a conductor path 1441 and/or a substrate 1450. The anchor 1421 mayhave a first thickness, such as approximately 2 micrometers. The anchor1421 may have anchor slots 1415, which extend through the anchor 1421,to provide area for thermal expansion of the anchor 1421. The anchorbeam interface 1425 on the anchor 1421 may have a second thickness thatmay be a number of times thicker greater than the first thickness of theanchor 1421, and may measure approximately 6 micrometers. The anchorbeam interface 1425 may be configured to provide tilt displacement,which is displacement in either the up or down direction at the contacttip 1427. The hinge 1423 may or may not be offset from the anchor beaminterface 1425 at the anchor beam interface end 1425A. The top edge ofthe hinge 1423 may or may not be co-planar with the top edge of theanchor beam interface end 1425A. The beam 1426 and the contact tip 1427may be arranged as discussed in previous embodiments. The conductorpaths 1441, 1443 and 1445 provide respective paths to the source, gateand drain connection points of the MEMS device 1420.

FIG. 15 provides a cross-sectional view of the switch device illustratedin FIG. 14. The MEMS device 1500 may include the switch 1520, thesubstrate 1540, and conductor paths 1541, 1543 and 1545. The switch 1520may include an anchor 1521, an anchor beam interface 1525, a hinge 1523,and a beam 1526.

The anchor 1521 may have a thickness B, which may be approximately 2micrometers. The anchor 1521 may have an air gap 1521-3 that may have awidth that allows for thermal expansion of the anchor material, whichmay be gold. The anchor 1521 may be configured to allow for an offsetbetween the anchor beam interface 1525 and the hinge 1523. The offsetmay allow the beam 1523 to be located approximately 0.6 micrometersabove the substrate 1530 and conductor paths 1543 and 1545. Although theoffset between the anchor beam interface 1525 and the beam 1523 is alsoshown in FIG. 15 at the top of the beam and the anchor beam interface,the tops of the anchor beam interface 1525 and the beam 1523 may nothave an offset, and may be co-planar in a horizontal plane (through theZ-axis).

The anchor beam interface 1525 may be formed from a conductive material,such as gold, and may have a thickness A. The thickness A may beapproximately 6 micrometers. The configuration of the anchor beaminterface 1525 allows for thermal expansion of the anchor beam interface1525 all directions upwards from the anchor 1521.

FIG. 16 illustrates a top-view of an exemplary configuration of a switchcomprising a MEMS device according to yet another embodiment of thepresent invention. An exemplary operation of the MEMS device 1600 willbe described with reference to FIG. 16. The exemplary MEMS device 1600includes a switch 1620, a substrate 1630, and conductor paths 1641, 1643and 1645. The top view of an exemplary MEMS device 1600 illustrated inFIG. 16 shows the layout of the conductor paths 1641, 1643 and 1645. Theswitch 1620 comprises anchor 1621, anchor beam interface 1625, beamassembly 1626, and contact tips 1627. The anchor 1621 makes contact withconductor path 1641. When the MEMS device 1600 is actuated by a signalpresent on conductor 1643, the switch 1620 responds with the beamassembly 1626 moving so contact tips 1627 contact conductor path 1645.This closes an electrical path between conductor path 1641 and conductorpath 1645. Of course, other conductor path configurations may bepossible.

FIG. 17 illustrates a sectional view of an exemplary configuration ofthe beam and anchor of a MEMS device according to another embodiment ofthe present invention. The MEMS device 1700 comprises an anchor 1721, asubstrate 1740, anchor beam interface 1725, and a hinge 1723. For easeof illustration and discussion, other components similar to thosedescribed with respect to other embodiments, for example, the beam andcontact tips, are also included in this embodiment.

In the illustrated embodiment, anchor 1721 further comprises anairbridge 1750. The airbridge 1750 may be an opening between thesubstrate 1740 and the anchor 1721 that extends from the anchor gap 1715beneath the anchor beam interface 1725 to the hinge 1723. The airbridge1750 may have a dimension C, which may be, for example, approximately0.60 micrometers. The airbridge 1750 may also cause the center portionof the anchor beam interface 1725 to rise above the edges as illustratedby notches 1725-9 located on both sides of the top of anchor beaminterface 1725. Of course, the dimensions of the airbridge 1750 inanchor 1721 may vary from wider to narrower and vice versa in alldirections, i.e., front (anchor gap 1715) to rear (hinge 1723), rear tofront, up (toward anchor beam interface 1725) to down (toward substrate1740) or down to up. In addition, the shape does not have to berectangular, but may be semi-circular, triangular, saw-toothed or anyshape that provides suitable stress-relieving properties. The presenceof airbridge 1750 may provide yet another area for expansion of theanchor beam interface 1725 and the anchor 1721.

FIG. 18 illustrates a cross-sectional view of an exemplary configurationof the beam and anchor of a MEMS device according to another embodimentof the present invention. The MEMS device 1800 comprises a substrate1840, and a switch 1820. The switch 1820 may comprise an anchor 1821, ananchor beam interface 1825, a hinge 1823, and a beam 1826. The anchor1821 comprises an anchor slot 1815, and an airbridge 1850. The airbridge1850, as explained above with respect to FIG. 17, may extend from theanchor slot 1815 through the anchor 1821 to the bottom edge of the hinge1823, thereby forming an opening between a portion of the anchor 1821and the substrate 1840. The airbridge 1850 may also cause the centerportion of the anchor beam interface 1825 to rise above the edges asillustrated by notches 1825-9 located on both sides of the top of anchorbeam interface 1825. The notches 1825-9 may or may not be present. Theairbridge 1850 opening may have a dimension C of approximately 0.60micrometers, which may not be uniform as explained above with respect toFIG. 17 and depending upon the shape of the airbridge.

The anchor beam interface 1825, the hinge 1823 and beam 1826 have athickness A, which may be approximately 6.0 micrometers. Due to theanchor 1821 located below the anchor beam interface 1825, the top edgeof the hinge 1823 and the beam 1826 may be offset from the top edge ofthe anchor beam interface 1825. When subject to expansion the anchorbeam interface 1825 may expand into the opening formed by the airbridge1850. This additional area for expansion further mitigates thedistortion of the switch 1820 when subject to thermal effects due tooperation and the environment.

The gap D between substrate 1840 and the hinge 1823 and the beam 1826may have a dimension of approximately 0.60 micrometers. In theillustrated embodiment, the dimensions of the airbridge opening C may beequal to the dimension gap D.

Those skilled in the art can appreciate from the foregoing descriptionthat the present invention can be implemented and constructed in avariety of forms. Therefore, while the embodiments of this inventionhave been described in connection with particular examples thereof, thetrue scope of the embodiments of the invention should not be so limitedsince other modifications will become apparent to the skilledpractitioner upon a study of the drawings, specification, and followingclaims.

What is claimed is:
 1. A micro-electro-mechanical switch device,comprising: a substrate having a plurality of gate connections, aplurality of source connections and a plurality of drain connections,and a plurality of switch structures, coupled to the substrate,comprising: a plurality of beam members, each having a length sufficientto overhang a respective gate connection and a respective drainconnection of the substrate, wherein each individual beam of theplurality of beams is connected to an adjacent beam by a crossconnection member; an anchor coupled to the substrate, the anchor havinga first thickness; a plurality of anchor beam interfaces coupling to theanchor and to the plurality of beam members, the anchor beam interfaceshaving a second thickness different from the first thickness; aplurality of anchor slots located in the anchor proximate to arespective one of the plurality of anchor beam interfaces; and aplurality hinges coupling to a respective one of the plurality of anchorbeam interfaces to a respective one of the plurality of beam members,each of the hinges flexing in response to a voltage differentialestablished between a respective one of the gate and the beam member,the plurality of hinges having a thickness that is the same as thesecond thickness.
 2. The micro-electro-mechanical switch device of claim1, wherein each of the plurality of hinges is offset in the verticalplane from the anchor beam interface.
 3. The micro-electro-mechanicalswitch device of claim 1, wherein the offset between the hinge and theanchor beam interface results in a tenths of micrometer gap between thebeam and a conductive path for a gate connection or the substrate. 4.The micro-electro-mechanical switch device of claim 1, wherein theoffset allows the top portion of the hinge and the top portion of theanchor beam interface to be coplanar.
 5. The micro-electro-mechanicalswitch device of claim 1, wherein the cross connection member is locatedcloser to the end of the beam opposite the anchor than the hinge.
 6. Themicro-electro-mechanical switch device of claim 1, wherein the crossconnection member is located in closer proximity to the hinge of a firstof the plurality of beams, and on an adjacent second of the plurality ofbeams, the cross connection member is located in closer proximity to theend of the adjacent second beam opposite the hinge of the adjacentsecond beam.
 7. The micro-electro-mechanical switch device of claim 1,further comprising a tip having an electrical contact at the end of thebeam opposite the hinge.
 8. The micro-electro-mechanical switch deviceof claim 1, wherein the anchor is an inverted U-shaped, comprising: atleast two anchor side walls; and a fixed width airbridge tie thatextends from one anchor side wall of the at least two anchor side wallsto the other of the at least two anchor side walls, thereby forming theinverted U-shaped anchor.
 9. The micro-electro-mechanical switch deviceof claim 1, the plurality of switch structures further comprising: aplurality of beam slots between the plurality of beam members, each ofthe slots extending from substantially the end of the beam member towardthe anchor, and at substantially the hinge extends inward, wherein thewidth of the hinge is less than the width of the respective beam member.10. The micro-electro-mechanical switch device of claim 1, each of theplurality of anchor beam interfaces comprising: an airbridge openingbetween the respective anchor beam interface and the substrate, and thatextends from a respective anchor slot of the plurality of anchor slotsto beneath a respective hinge of the plurality of hinges.